The invention relates to an electromagnetically compensating beamless dynamometer or weighing machine having a work coil movable in the working air gap of a magnet arrangement held stationary and a parallel construction with two elastic links which are arranged in planes staggered in the direction of movement and are attached to a bracing part maintained stationary and to a rigid connecting element movable with the work coil so as to form a parallelogram, and each of which exhibits two arms of equal length staggered in a plane.
Machines of this type are known. In them the arms of the links are customarily aligned mutually parallel (e.g. CH-PS 521 575).
An apparatus is also known (US-PS 3 191 702) in which the links are of E-shaped construction and the two outer tongues are attached to the part maintained stationary, whereas the rigid connecting element is attached to the end of the central tongue of each link which is likewise directed towards the part maintained stationary.
These known constructions suffer from the disadvantage then when lateral forces or a corner load are absorbed a complicated distribution of forces occurs in their links which renders the interpretation very difficult and necessitates a robust construction of the links. In both cases the links exhibit a wide base on their side remote from the part maintained stationary, which dictates a relatively large overall bulk.
A top-pan balance is also known (DT-Gbm 71 15 570) wherein the links are attached to the movable part of the guide means at any one point and exhibit substantially the form of a triangle, whilst the bearing positions lie at least approximately in the corner points of this triangle. It is intended by the triangular configuration of the links to avoid any static over-determination in order to simplify the calculation and interpretation.
If this version is to be constructed as electromagnetically compensating, then the part receiving the force to be measured or the load to be weighed, i.e. the pan in the case of a top-pan balance, must lie with its median axis on the line connecting the two apices of the triangles, because in the case of a displacement of the median axis out of the connecting line, lateral forces cause torques which cannot be absorbed satisfactorily by the triangular links due to the fact that each link is fastened to the moving part in only one point.
Lastly, an electromagnetically compensating beamless dynamometer or weighing machine is known (DT-Gbm 72 05 983) in which the links are of annular construction. Although this known construction permits a compact assembly, nevertheless the so-called "Knackfrosch" effect occurs easily in the links of annular construction, so that this guide system is unsuitable for precision balances and even finer balances.